Surface treatments are known for parts made of ferrous alloys, in order to increase the resistance of said parts to seizing and surface wearing. Other treatments are known, which improve the resistance of such parts to corrosion. But if, in addition, the variations in the total resistance of said parts to fatigue and to brittleness, or the variations in the adsorption of the oil film on the surface of the parts, as a result of any such known treatment, are taken into consideration, one finds that at the present time there exists no treatment enabling at least five out of the six above-mentioned mechanical characteristics to be improved, the sixth one, at the worst, remaining unchanged.
The object of the present invention is to reconcile the various requirements. It relates to mechanical parts made of ferrous alloys which are treated in a manner such that, according to the invention, said parts are coated with a novel layer, having surprising properties, and called hereinafter "the layer". A part coated with the layer increases substantially five of its mechanical characteristics mentioned hereinabove, that is, its resistance to seizing, to wear, to corrosion, and to shocks, as well as its ability to adsorb the oil film highly, while its sixth characteristic, that is, its overall resistance to fatigue, is not altered.